Add v8_os_page_size flag for cross compilation

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 2311ad70fb6099b7090181e15f580682ac1b156a..9bcfb089efabbe1c227662a4a5532d6655e4a934 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -65,6 +65,9 @@ declare_args() {
   # Switches off inlining in V8.
   v8_no_inline = false
 
+  # Override os page size when generating snapshot
+  target_os_page_size = "0"

[Michael Lippautz, 2016/11/14 09:24:43]

I'd make this v8_target_os_page_size. Not sure we need "target" in the name, as
we basically just override the os page size.

[Michael Achenbach, 2016/11/14 09:59:01]

Yes, please add a v8_ prefix. I don't care about the rest of the name, but we'd
like to know which args are from V8 in a chromium context.

+
   # Similar to vfp but on MIPS.
   v8_can_use_fpu_instructions = true
 
@@ -671,6 +674,13 @@ action("run_mksnapshot") {
     ]
   }
 
+  if (target_os_page_size != "0") {
+    args += [
+      "--target_os_page_size",
+      target_os_page_size,
+    ]
+  }
+
   if (v8_use_external_startup_data) {
     outputs += [ "$root_out_dir/snapshot_blob.bin" ]
     args += [